Relationship Between Age and Trajectories of Rehospitalization Risk in Older Adults

Abstract

Objectives: To characterize the magnitude and duration of risk of rehospitalization according to age after hospitalization for heart failure (HF), acute myocardial infarction (AMI), or pneumonia.

Design: Retrospective cohort study.

Setting: U.S. hospitals (n = 4,767).

Participants: All Medicare fee-for-service beneficiaries aged 65 and older surviving hospitalization for HF, AMI, or pneumonia between October 2012 and December 2013.

Measurements: Daily risk of first rehospitalization for 1 year after hospital discharge was calculated according to age category (65-74, 75-84, ≥85) after adjustment for sex, race, comorbidities, and median ZIP code income. Time required for adjusted rehospitalization risk to decline 50% from maximum value after discharge, time required for adjusted risk to approach a plateau period of minimal day-to-day change, and degree to which adjusted risk was higher in recently hospitalized individuals than in the general elderly population were identified.

Results: There were 414,720 hospitalizations for HF, 177,752 for AMI, and 568,304 for pneumonia. The adjusted risk of rehospitalization declined with increasing age after HF hospitalization (P < .001), rose with increasing age after AMI hospitalization (P < .001), and was slightly lower with increasing age after pneumonia hospitalization (P = .002). Adjusted risks of rehospitalization were high beyond 30 days after hospitalization for all ages.

Conclusion: Although older age has heterogeneous relationships with rehospitalization risk, risk of readmission remains high for an extended time after discharge regardless of age or admitting condition. Condition-specific data on risk can be used to guide discussions on advanced care planning and strategies for longitudinal follow-up after hospitalization.

Keywords: cardiovascular disease; geriatrics; pulmonary diseases; quality of care; readmission.

Figure 1. Adjusted Risk of First Rehospitalization by Age after Hospitalization for Heart Failure or Acute Myocardial Infarction

Risk is described using daily hazard rates that have been adjusted for sex, race, median income of the zip code of residence, and comorbidities. To illustrate the heterogeneous relationship of rehospitalization risk with age across admitting conditions, data is shown for older patients 65–74 years-old and 85+ years-old who were discharged after hospitalization for heart failure or acute myocardial infarction. Adjusted readmission risk trajectories are shown for the full year after hospitalization.

Figure 2. Relative Risk of First Hospitalization by Age after Hospitalization for Heart Failure or Acute Myocardial Infarction Compared with the General Elderly Population

Post-discharge populations have been directly standardized to the Medicare FFS population with respect to sex, race, and median income of the zip code of residence. Illustrative data is shown for older patients 65–74 years-old and 85+ years-old who were discharged after hospitalization for heart failure or acute myocardial infarction. In 2013, the 30-day and 1-year cumulative incidence of hospitalization among Medicare FFS beneficiaries was 1.6% and 19.6%, respectively. Relative risks of first rehospitalization by age are shown for the full year after hospitalization.